The present invention relates to vacuum filter assemblies for filtering a feed liquid into a filtrate container. The invention is particularly useful in biological filters used to clarify and sterilize biological solutions such as tissue culture media, and is therefore described below with respect to such an application.
Biological filter assemblies commonly comprise three main parts, namely: a container for the unfiltered feed liquid, a container for the filtrate, and a membrane interposed between the two containers. Examples of such filters are described in U.S. Pat. Nos. 4,357,270, 4,689,147 and 4,702,834. More recently, biological filters have appeared on the market which do not include the filtrate container, but instead are mounted on non-disposable, sterilizable filtrate containers, such as glass bottles.
The above types of biological filter assemblies have a number of drawbacks which make them cumbersome and inconvenient. Thus, they are very bulky, since the feed-liquid container and filtrate container are high volume components and therefore take up a large amount of space, particularly as these devices are disposable and large numbers of these filters are used in biological laboratories. Also, filling the feed-liquid container is inconvenient, which is especially so for the funnel-type filters where the volume of the filtrate container is larger than that of the plastic funnel used in such filter assemblies, thereby requiring the funnel to be refilled a number of times to fill a single filtrate container. This is particularly cumbersome since the feed liquid containers are frequently heavy and hard to lift. Further, should the filter plug during the filtration of a batch, transferring the remaining feed liquid to a new filter is also extremely cumbersome.